Patent GB-266921-A (GB)
Title: Improvements in power mechanism for typewriting machines
IPC: B41J23/12
Filed: 1926-03-30
Abstract: 266,921. Marks, E. C. R., (North East Appliances, Inc.). March 30, 1926. Relay actions; back-spacing mechanism. - Relates to relayactions of the kind equipped with a driving-roller co-operating with key-controlled cam-units, and comprises a detachably mounted driving-roller, a construction of cam-unit, a special cam-unit for operating back-spacing mechanism, and driving-mechanism for the driving-roller comprising an electromotor provided with a speedcontroller. The driving-roller 22 runs on a shaft 24 detachably mounted in a frame 21, the ends of the shaft entering sockets 26, shown in bottom plan in Fig. 2, and being secured by means of latches 27 which are released to permit of the shaft and roller being moved downwards out of operative position for adjustment or repair. The shaft is preferably mounted in a pivoted bail 30 which permits of the shaft and roller being moved downwards without becoming detached from the frame. The arms of the bail are sprung apart when it is required to detach the shaft and roller. When the shaft is in operative position, a worm 32, Fig. 2, thereon gears at the top with a worm a shaft 33 reared to a shaft 37 driven by an electromotor 38. The frame 21 is arranged under the typewriter 20 and carries the relay mechanism as a unit. The driving-roller co-operates with front and rear sets of cams 23 for operating typelevers 53, and co-operates also with cams controlled by the spacing and back-spacing keys. The cams 23 are carried by bell-cranks 40 consisting of two side plates having the horizontal arms riveted together and the vertical arms separated by studs 42, 43. The studs 43 bear in blocks 44 secured by screws to bars 45, 46 on the frame 21, the blocks Entering recesses 48 and having shoulders engaging the sides of the bars. The bell-cranks are connected bv links 55 to sublevers 53 engaging the type-levers. The cams aro pivoted on the studs 42 and are formed with flanges having two serrated cam-sectors 61, Fig. 4, separated by concave parts. Each bell-crank is provided with a spring-urged pivoted arm 63 which tends to rotate the associated cam bv engaging one of two projections 62 thereon, rotation being normally prevented by engagement of one of two projections 64 on the cam with a lug 66 on a pivoted arm 67 on the bellcrank. The arms 63, 67 are independently mounted on a common pivot 68. The arms 67 have lugs 72 engaging the forked ends of arms 79 on the key-levers 73, the arms 79 being guided by a slotted plate 80 secured to the bars 45, 46. The slots have enlargements for guiding the links 55, and the plate is formed at the middle with a comb 81 for guiding the bell-cranks 40. On slightly depressing any of the key-levers, the associated arm 67 releases the cam-projection 64 and the arm 63 turns the cam until one of the serrated sectors engages the driving-roller. engagement being maintained by the returning- spring 57 of the sub-lever 53. The cam is thereupon rotated, the bell-crank is rocked, and the type-lever is swung for impression. When the peak of the cam-sector passes the driving-roller a half-revolution of the cam is completed by the arm 63 and, since release of the key-lever does not occur during this period, the approaching cam-projection 64 is caught by a lug 65 on the arm 67. On release of the key-lever the projection 64 is released by the lug 65. and caught by the lug 66. The key-levers have arms 74 engaging a pivot 75, and forward extensions 173 entering slots in a comb 84. Mounted in a metal channel 83. A cam-unit 190, Fig. 1, operates back-spacing mechanism of the kind comprising a pawl-arm 95 pivoted on a rocking arm 97 and connected to a driving-link 94, the arm 97 being initially rocked to engage the pawl 99 with the feed-rack 100, and the pawl-arm being then rocked to effect back-spacing. The cam 90 is mounted on a bell-crank 40 connected to, a rockshaft 92 operating the link 94, the back-spacing key controlling the arm 67 of the cam-unit. The cam performs. one revolution at each operation, being provided with only two projections for co-operation with the arms 63, 67. The serrated part of the cam is so designed that after the arm 97 has been moved rapidly the pawl-arm 95 receives an accelerated and then a retarded movement. Driving-mechanism. - To reduce noise the electromotor 38, Fig. 2, is mounted on plugs 143 of cork &c. The speed is controlled by means of a contact-arm 118, Figs. 2 and 15, movable over studs 117 by turning a finger-piece 120 which is associated with devices for arresting the contactarm on the stud corresponding to a predetermined speed, and for returning the contact-arm to the off position. The finger-piece is connected to a plate 122 having a roller 124 engaging lugs 125 on the contact-arm. A spring latch 136 pivoted on the plate is adapted to arrest the contact-arm when on a predetermined stud by entering a notch in a plate 126 adjustable by turning a graduated knob 140. The plate 126 is retained by a detent 130 co-operating with notches therein. On pressing a spindle 139 the latch is released and the contact-arm is returned by springs to the off position. Space-key actions.-A space-key 85, Figs, 1 and 2, controlling one of the cam-units 23 is secured to a key-lever and is supported also by means of a cranked spindle 87 engaging lugs 86 on the space-key and pivoted in brackets 89 on the member 83. Locking-devices.-A keyboard-locking bar 113, Fig. 1, pivoted on the brackets 89, is moved by the line-locking stop into engagement with shoulders 114 on the arms 173 of the key-levers 73. When the above-described motor controller is in the off position, an arm 135 on the plate 122 moves the locking-bar into locking position by engaging fingers 142 thereon.